clarify beta apis off by default

keps/prod-readiness/sig-architecture/3136.yaml

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+kep-number: 3136
+stable:
+  approver: "@wojtek-t"

keps/sig-architecture/3136-beta-apis-off-by-default/README.md

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+# KEP-3136: Beta APIs Are Off by Default
+
+<!--
+This is the title of your KEP. Keep it short, simple, and descriptive. A good
+title can help communicate what the KEP is and should be considered as part of
+any review.
+-->
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+<!--
+A table of contents is helpful for quickly jumping to sections of a KEP and for
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+  <code>&lt;!-- toc --&rt;&lt;!-- /toc --&rt;</code>
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+<!-- toc -->
+- [Release Signoff Checklist](#release-signoff-checklist)
+- [Summary](#summary)
+- [Motivation](#motivation)
+  - [Goals](#goals)
+  - [Non-Goals](#non-goals)
+- [Proposal](#proposal)
+  - [User Stories (Optional)](#user-stories-optional)
+    - [Story 1](#story-1)
+    - [Story 2](#story-2)
+  - [Notes/Constraints/Caveats (Optional)](#notesconstraintscaveats-optional)
+  - [Risks and Mitigations](#risks-and-mitigations)
+- [Design Details](#design-details)
+  - [Test Plan](#test-plan)
+  - [Graduation Criteria](#graduation-criteria)
+    - [GA](#ga)
+  - [Upgrade / Downgrade Strategy](#upgrade--downgrade-strategy)
+  - [Version Skew Strategy](#version-skew-strategy)
+- [Production Readiness Review Questionnaire](#production-readiness-review-questionnaire)
+- [Implementation History](#implementation-history)
+- [Drawbacks](#drawbacks)
+- [Alternatives](#alternatives)
+- [Infrastructure Needed (Optional)](#infrastructure-needed-optional)
+<!-- /toc -->
+
+## Release Signoff Checklist
+
+<!--
+**ACTION REQUIRED:** In order to merge code into a release, there must be an
+issue in [kubernetes/enhancements] referencing this KEP and targeting a release
+milestone **before the [Enhancement Freeze](https://git.k8s.io/sig-release/releases)
+of the targeted release**.
+
+For enhancements that make changes to code or processes/procedures in core
+Kubernetes—i.e., [kubernetes/kubernetes], we require the following Release
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+- [ ] (R) Enhancement issue in release milestone, which links to KEP dir in [kubernetes/enhancements] (not the initial KEP PR)
+- [ ] (R) KEP approvers have approved the KEP status as `implementable`
+- [ ] (R) Design details are appropriately documented
+- [ ] (R) Test plan is in place, giving consideration to SIG Architecture and SIG Testing input (including test refactors)
+  - [ ] e2e Tests for all Beta API Operations (endpoints)
+  - [ ] (R) Ensure GA e2e tests for meet requirements for [Conformance Tests](https://github.com/kubernetes/community/blob/master/contributors/devel/sig-architecture/conformance-tests.md) 
+  - [ ] (R) Minimum Two Week Window for GA e2e tests to prove flake free
+- [ ] (R) Graduation criteria is in place
+  - [ ] (R) [all GA Endpoints](https://github.com/kubernetes/community/pull/1806) must be hit by [Conformance Tests](https://github.com/kubernetes/community/blob/master/contributors/devel/sig-architecture/conformance-tests.md) 
+- [ ] (R) Production readiness review completed
+- [ ] (R) Production readiness review approved
+- [ ] "Implementation History" section is up-to-date for milestone
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+- [ ] Supporting documentation—e.g., additional design documents, links to mailing list discussions/SIG meetings, relevant PRs/issues, release notes
+
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+**Note:** This checklist is iterative and should be reviewed and updated every time this enhancement is being considered for a milestone.
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+
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+[kubernetes/kubernetes]: https://git.k8s.io/kubernetes
+[kubernetes/website]: https://git.k8s.io/website
+
+## Summary
+
+New beta APIs will not be enabled in clusters by default.
+Existing beta APIs and new versions of existing beta APIs, will continue to be enabled by default: 
+if v1beta.some.group is currently enabled by default and we create v1beta2.some.group, v1beta2.some.group will still be enabled by default.
+
+## Motivation
+
+Beta APIs are not considered stable and reliance upon APIs in this state leads to exposure to bugs,
+guaranteed migration pain for users when the APIs move to stable, and the risk that dependencies will
+grow around unfinished APIs.
+Enabling beta APIs by default, exacerbates these problems by making them on in nearly every cluster.
+We observed these problems as we removed long-standing beta APIs and the PRR survey tells us that over
+90% of production clusters leave these APIs enabled.
+Unsuitability for production use is documented at https://kubernetes.io/docs/reference/using-api/#api-versioning 
+("The software is not recommended for production uses"), but defaulting on means they are present in nearly every 
+production cluster.
+By disabling beta APIs by default, a cluster-admin can opt-in for specific APIs without having every
+incomplete API present in the cluster.
+
+### Goals
+
+1. Disable new beta APIs by default.
+2. Continue enabling existing beta APIs and new version of existing beta APIs by default:
+   if v1beta.some.group is currently enabled by default and we create v1beta2.some.group, v1beta2.some.group will still be enabled by default.
+3. Allow enabling specific resources in beta.  Enable coolnewjobtype.v1beta1.batch.k8s.io without enabling other-neat-job.v1beta1.batch.k8s.io
+
+### Non-Goals
+
+1. Change featuregate defaults.
+
+## Proposal
+
+New beta APIs will be placed into the `DisableVersions` stanza instead of the `EnableVersions` stanza (see [DefaultAPIResourceConfigSource](https://github.com/kubernetes/kubernetes/blob/0669da445fa8c1ae07c15c0827f0e83da11cbe58/pkg/controlplane/instance.go#L643)).
+The `--runtime-config` flag will be extended to allow `group/version/resource=true`, to enable specific resources.
+To enable a beta API, a cluster-admin will have to add the appropriate `--runtime-config` flags.
+
+### User Stories (Optional)
+
+#### Story 1
+
+As a cluster-admin I want to enable the coolnewjobtype.v1beta1.batch.k8s.io API in my cluster.
+
+To do this I call `kube-apiserver --runtime-config=batch.k8s.io/v1beta1/coolnewjobtype`.
+
+#### Story 2
+
+As a cluster-admin I want to enable all beta APIs as in past releases.
+
+To do this I call `kube-apiserver --runtime-config=api/beta=true`.
+This already exists and will continue to function.
+
+
+### Notes/Constraints/Caveats (Optional)
+
+### Risks and Mitigations
+
+Adoption of beta features will slow.
+Given how kubernetes is now treated, this is a good thing, not a bad thing.
+Those users that want to move quickly and get new features can do so by enabling all beta feature
+or just enabling those that are important for their workload.
+The [PRR survey](https://datastudio.google.com/reporting/2e9c7439-202b-48a9-8c57-4459e0d69c8d/page/Cv5HB) shows that 
+over 30% of production clusters have alpha features enabled, so clsuter-admins are willing and able to enable features
+that are not on by default when they are desired.
+
+## Design Details
+
+<!--
+This section should contain enough information that the specifics of your
+change are understandable. This may include API specs (though not always
+required) or even code snippets. If there's any ambiguity about HOW your
+proposal will be implemented, this is the place to discuss them.
+-->
+
+### Test Plan
+
+Integration tests will be written to ensure that no new beta APIs are enabled in the kube-apiserver by default.
+Unit tests will be written to ensure that the new flag functionality works as expected.
+
+### Graduation Criteria
+
+This KEP is a policy KEP, not a feature KEP.  It will start as GA.
+
+#### GA
+
+- Integration and unit tests from above.
+- updating the enablement docs for beta
+  - https://kubernetes.io/docs/reference/using-api/#api-versioning
+  - https://kubernetes.io/docs/reference/command-line-tools-reference/feature-gates/#using-a-feature 
+    Even though that is talking about feature gates, it is likely worth calling out there that new beta REST APIs are no
+    longer enabled by default)
+
+### Upgrade / Downgrade Strategy
+
+The additional command line flag format for `--runtime-config` will not be recognized on older levels of kubernetes.
+This means that when downgrading, cluster-admins will have to adjust their CLI arguments if they opted into a new beta API.
+This is congruent to flag handling for new features today.
+Because this only impacts new beta APIs, there is no behavior change for existing APIs on upgrade.
+
+### Version Skew Strategy
+
+Because this only impacts new beta APIs, there is no novel skew risk.
+
+## Production Readiness Review Questionnaire
+
+Not applicable because this is a policy KEP.
+
+## Implementation History
+
+<!--
+Major milestones in the lifecycle of a KEP should be tracked in this section.
+Major milestones might include:
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+## Drawbacks
+
+<!--
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+-->
+
+## Alternatives
+
+<!--
+What other approaches did you consider, and why did you rule them out? These do
+not need to be as detailed as the proposal, but should include enough
+information to express the idea and why it was not acceptable.
+-->
+
+## Infrastructure Needed (Optional)
+
+<!--
+Use this section if you need things from the project/SIG. Examples include a
+new subproject, repos requested, or GitHub details. Listing these here allows a
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